Manufacture of artificial silk



Jan. 15, 1935.

C ORRU GA TED 6005715 /4 o come/.1 GA TED Original Filed April 17, i934 Patented Jan. 15, 1935 UNITED STATES MANUFACTURE OF ARTIFICIAL SILK Adrian J. L. Moritz, Enka, N. 0., asslgnor to American Enka Corporation, Enka, N. 0., a corporation of Delaware Original application April 1'1, 1934, set-1.1 No.

Divided and this application Septemher 17, 1934, Serial No. 744,399

3 Claims.

This application is a division of my application Serial Number 721,044, filed April 17th, 1934.

The invention relates to the art of manufacturing artificial silk, and more particularly to a I process of and apparatus for forming freshly spun artificial silk threads and the like into packages, which threads possess desirable qualities such as relatively high tensile strength, uniformity in denier, and improved dyeing properties. The invention is applicable to the production of artificial silk threads and the like when formed in accordance with'the viscose process, but with slight modifications this method maybe equally well employed in the production of artificial silk threads when formed by any of the known processes such as the cuprammonium process, the acetate process or the nitrocellulose process.

It has been recognized in the past that the tensile strength and dyeing properties of the finished artificial silk thread may be greatly improved if the thread is placed under tension while it is still fresh after its passage from the spinning bath. Numerous methods have been proposed for accomplishing the giving of uniform tension to succeeding portions of the thread, and of these methods one involves the use of a series of glass rods arranged in the path of the thread between the spinnerets and a collecting device so that the threads may be interlaced with the rods in such manner as to provide a braking or drag action upon the thread. While the practice of this method did produce certain beneficial results, it has been found that the method is not entirely satisfactory since the braking action with the resultant tension placed upon the thread has been found in most instances to be of an irregular and uneven character.

It has been proposed in this art to lead the thread from the spinning bath to a pair of positively driven cylinders or drums in such manner that the thread contacts with only a small portion of the periphery of each of said drums, and this procedure was carried out for the purpose of obtaining a constant stretch of succeeding portions of the thread as they passed between the drums since the second drum was operated at a higher peripheral speed than the first one. The thread after being stretched was then passed to the collecting device. In a modified procedure involving the general method just referred to, a collecting or winding number was substituted for the second drum and the peripheral speed of said winding devices was caused to be operated at a constant higher peripheral speed with respect to that of the first drum so as to effect a stretch between the drum and the winding member.

In still another of the proposed methods for effecting the tensioning and stretching ofthe thread, a pair of positively driven drums are employed with the thread being passed entirely around the circumference of each of the drums, one or more times, whereby when the second drum in the path of travel oi. the thread is operated at a higher peripheral speed than the first, the thread as it passes between the drumsis stretched at a constant rate with respect to succeeding portions thereof before it is passed to a collecting device for packaging. However, so far as I am aware, these methods heretofore proposed have not proven entirely satisfactory be cause uncontrolled slippage occurs between the thread and the respective drums in some instances so that a very irregular pull is exerted on the thread with no uniformity in the size of the thread being obtained while, when substantially no slippage occurs so that a constant stretch is given to the thread, the method fails to compensate for certain mechanical and chemical irregularities inherent in any process of spinning artificial silk produced from cellulosic solutions.

Another recent development involves the use of a plurality of idling rollers arranged in a group at one place in the path of travel of the thread from its place of formation to the collecting device, and the thread is drawn over these rollers by a drawing godet which is contacted by the thread in such a manner that slippage is permitted between this godet and the thread. Such a process is intended to be used so as to compensate for the mechanical and chemical irregularities inherent in the formation of the thread. This prior process as defined permits of a control of the drag placed upon the thread by its contact with the idling rollers due to the employment of braking means for the respective idling rollers, and while this process does to some extent compensate for the irregularities above referred to, such irregularities are not entirely compensated for and the present invention is intended as an improvement thereover.

An object of the present invention is to overcome the difficulties heretofore encountered in the production of artificial silk threads and the like, such as results from the irregularities in the mechanical equipment and chemical failures inherent in the formation of artificial silk threads, and the invention contemplates an apparatus by which the present process can be emciently practiced wherein a uniform stretch of the thread duce a body of yarn can be had irrespective of the irregularities in the size and character of the. spun filaments.

Other advantages and objects will be apparent from the following detailed description when considered in connection with the accompanying drawing wherein Fig. 1 is a diagrammatical front view of one form of the invention,

Fig. 2 is a ditical side view of the structure shown in Fig. 1,

Fig. 3 is a diagrammatical view of the modified form of apparatus made in accordance with this invention, and

Fig. 4 is a side view of F 3.

Before referring to the drawing in detail it is well to set forth more specifically examples of the problems encountered and the broad method for overcoming the same. It is clear that toproeven dyeing properties, the yarn should have even denier throughout and the stretching of the thread to produce this result should be constant providing contraction is compensated for so that the thread will ultimately be of uniform denier. One of the conditions tending to interfere with the obtaining of this result is that a somewhat variable action is had in the setting bath on the freshly extruded or spun cellulosic solution andsuch variable action or fluctuation in the action of the setting bath causes the thread as it emerges therefrom to be non-uniformly coagulated. As an example, it is well to consider a short section of thread as it emerges from the spinneret. Should this section of the thread be subjected to excessive coagulation by the fluctuation in the action of the setting bath, this section of the thread would be slightly harder than the average section of the thread and would therefore oppose or resist the stretching action which is to be given to the thread. However, if another section of the thread should be coagulated to a degree slightly less than the average coagulation of the thread as a whole, this section would oppose the stretching with considerable less resistance and therefore if no compensation is made for this irregularity in the coagulation, that portion of the thread which does not resist the stretching will be drawn to a much finer denier than the other portion referred to and may possibly be broken in the further processing of the thread. Additionally, drawing rollers of the type commonly used in this art for stretching the thread tend to rotate with an eccentric action for the reason that it has been found to be substantially impracticable to exactly center such rollers on a positively driven shaft in a manner so that all portions of the periphery thereof rotate about the axis with the same linear speed as the other portions. Furthermore, such rollers have been found to wear unevenly in a very short period of time so that practically all of the rollers after a short period of operation have eccentrically arranged portions along their peripheries. The employment of such rollers results in the thread which is wound thereabout, being caused to travel at a greater peripheral speed when contacting with the portions of the rollers which are the greatest distance from the roller axis, than is the thread contacting with the portions of the periphery of the roller which are on a lesser radius from the roller center. It will be seen that the use of such a roller results in an abnormal stretch in the thread and must be compensated for if this condition is to be corrected.

the structure shown in Now referring to the drawing in detail, numeral 10 designates a spinneret which is immersed in a setting bath and the thread which is extruded and passed from the setting bath is designated as 11. The thread is conducted over a thread guide 12 and is thereafter passed to a drawing roller or godet wheel 13, which roller the thread partially encircles. From the roller 13 the thread passes over another thread guide 14 and it is then conducted to another corrugated roller or godet 15. The thread is caused to encircle the roller 15 a plurality of times in order to insure a substantially non-slip engagement therewith. After encircling the roller 15 the thread is conducted to a spinning pct 16 or to some other suitable form of collecting device such as a bobbin and the like. The preferred manner in which the thread is passed around the corrugated rollers and over the respective thread guides is readily apparent from a consideration of Fig. 2, but it is to be understood that the thread in passing around the roller 13 law directed with respect to the periphery of said roller, due to the disposition of the thread guides 12 and 14, that the thread contacts with the roller less than 360 of its circumference and preferably contacts with the roller for approximately 280 of its circumference. In addition to this since the roller 13 has a corrugated surface the thread is contacting only with the raised portions of the surface and thus assured substantial slippage of the thread with respect to the roller 13.

In the form of apparatus illustrated in Figs. 3 and 4, the thread is conducted from the spinning bath in which the spinneret 10 is immersed, to a corrugated roller 13a over which it is passed without being encircled entirely around the same, and the thread is then conducted to a corrugated roller 15a about which it is wrapped a sufilcient number of times to assure against any substantial slippage. The thread, after it is passed around roller 15a is then conducted to a collecting device 16a. No particular means for driving the positively propelled rollers or godets 13 and 15 and 13a and 15a, have been illustrated, but it is to be understood that any suitable means may be used for this purpose, it being intended that the rollers 15 and 15a be operated at a greater peripheral speed than the rollers 13 and 13a respectively in order that a stretching of the thread may be had between the rollers.

The compensation for chemical and mechanical irregularities in the formation of the thread and the processing thereof before it is packaged is an important feature of this invention and as has already been stated the compensation for mechanical and chemical irregularities in the production of the thread may be had by permitting a slippage of the thread with respect to the withdrawal godet 13 and 13a while driving the godets 15 and 15a at a greater speed with respect to the godets first contacted by the thread. It is intended that substantially no slippage occurs between the thread and the godets 15 and 150.

In carrying out the process in the manner above set forth if a small section of the thread is coagulated in excess of the average so that it has an increased resistance to stretching, this stiffer section of thread will be caused to be wound tighter around the first roller 13 or 13a, that is it will adhere more closely thereto and consequently the slippage will be temporarily diminished or eliminated and the stretch will be increased so as to thus compensate for the irregularity. If, however, a section of the yarn is coagulated to a de- 'the like through a coagulating'bath, subjecting gree inferior to the average coagulation of the thread then the friction on the roller 13'or 13a will decrease and an increased slippage occurs so that the lesser coagulated section will not be stretched to an undesired extent.

The same general action in the operation as above referred to will be had when eccentric portionson the peripheries of the rollers 15 and 15a are encountered since the eccentric action of the drawing roller already referred to tends to cause the thread to be pulled at a higher speed at certain points. The variations in the pull on the thread are compensated for by the slippage of the thread on the first roller whether the eccentricity exists ineither or, both of the rollers. When a greater pull is given to the thread, the thread being slidably engaged with the periphery of the first roller, travels at a higher speed than the periphery of the roller and thereby relaxes the tension on the section of thread between the rollers. Thus while the slippage on the first roller overcomes the variations in the freshly spun thread as it leaves the spinning bath, and the normal eccentric action of both rollers, the second roller,

rotating at a higher peripheral speed than the first roller, causes the thread to be stretched between the rollers and the second roller which may be either 15 or 15a imparts a constant and substantial uniform tension to the thread before it is taken up by the collecting device.

Whereas, the term packages has been employed throughout the description, it is to be understood that either bobbins or centrifugal pots may be used as the collecting devices, as the form of collecting device employed is immaterial in applying the novel features of the present invention.

I claim: 1. A method of manufacturing artificial silk which comprises extruding a thread, filament, or

the thread to a stretching action between two or more corrugated godet, wheels during its travel to a collecting device by passing the thread around the said corrugated godet wheels which are rotating at different peripheral speeds, and allowing substantial slippage on the first godet wheel only,

by causing the thread to contact with the said first godet wheel less than 360 of its circumference. e

2. A methodv of manufacturing artificial silk which comprises extruding a thread, filament, or the like through a coagulating bath, propelling and stretching the thread at two or more spaced points in advance of a collecting device by giving the thread the desired amount of friction contact with a godet wheel at each of the spaced points, and compensating for tension variations occurring in the system, by passing the thread, at the first spaced point, around the godet wheel less than 360 of its circumference to thereby permit slippage.-while propelling the thread at the nextspaced point in such a manner as to prevent slippage.

3. A method of manufacturing artificial silk which comprises extruding a thread, filament, or the like through a coagulating bath, stretching the thread in its path of travel between the point of extrusion and a collecting device by passing the same around a driven corrugated godet wheel less than 360 to permit slippage thereon, causing the thread to contact with a second godet wheel rotating at a higher peripheral speed, said contact being greater than 360 to prevent slippage and thereby stretch the thread while compensating for tension variations occurring in the system, and finally collecting the thread;

ADRIAN J. L. MORITZ. 

